Process to produce biaxially oriented polylactic acid film at high transverse orientation rates

a polylactic acid film, high transverse orientation technology, applied in the direction of transportation and packaging, other domestic articles, synthetic resin layered products, etc., can solve the problems of ineffective production of bopla films, film breakage is very prone to happen, and the biaxial orientation rate of bopla films is limited

Inactive Publication Date: 2009-06-11
TORAY PLASTICS AMERICA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0030]This invention provides a method to allow the transverse orientation of BOPLA films at high orientation rates in excess of 6 TDX (transverse direction orientation rate) and typically in the range of 8-11 TDX, similar to BOPP transverse direction orientation rates. This is significantly higher than what has been achieved in prior arts. Such a film composition can result in biaxially oriented PLA films that are more economical than the current art for BOPLA and can enable the use of BOPP assets to make BOPLA films without significant capital expense and modifications.

Problems solved by technology

Unfortunately, biaxially oriented PLA (BOPLA) films have been found to be limited to relatively low orientation rates when compared to BOPP manufacturing.
If BOPLA films are oriented in the transverse direction higher than a nominal 3-5×, film breaks are very prone to happen and production of BOPLA films cannot be effectively achieved.
Moreover, if sustainable transverse orientation at 3-5× is maintained, usable film width for many packaging converters and end-users become limited and can result in wasted film and less productivity.
However, the film is not suitable for high transverse orientation rates in excess of 6 TDX; the highest TDX cited in the examples is 5.5.
In addition, the use of polyolefin additives such as polypropylene or polyethylene will cause incompatibilities with the polylactic acid polymer resulting in a hazy film appearance.

Method used

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  • Process to produce biaxially oriented polylactic acid film at high transverse orientation rates
  • Process to produce biaxially oriented polylactic acid film at high transverse orientation rates
  • Process to produce biaxially oriented polylactic acid film at high transverse orientation rates

Examples

Experimental program
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Effect test

example 1

[0064]A 2-layer coextruded biaxially oriented PLA film was made using sequential orientation on a 1.5 meter wide tenter frame line, the film includes a core layer substantially of Natureworks® 4032D at about 96 wt % of the core layer and dry-blended with about 4 wt % of DuPont Biomax® 120 ethylene-acrylate copolymer. The coextruded heat sealable skin layer includes Natureworks® 4060D at about 94 wt % of the skin layer. An antiblock masterbatch of 5 μm silica at a loading of 5 wt % of the masterbatch in a carrier resin of amorphous PLA (4060D) was added to the coextruded heat sealable skin layer at about 6 wt % of the skin layer for an effective antiblock loading of 3000 ppm. This antiblock masterbatch was provided by Clariant Oman® bl-698585.

[0065]The total thickness of this film substrate after biaxial orientation was ca. 80 G or 0.8 mil or 20 μm. The thickness of the respective heat sealable resin layer after biaxial orientation was ca. 6 G (1.5 μm). The thickness of the core laye...

example 2

[0066]A process similar to Example 1 was repeated except that the core layer included about 66 wt % of crystalline 4032D, 30 wt % of amorphous PLA 4060D, and 4 wt % of ethylene-acrylate copolymer. The transverse orientation rate obtained was 10.6×.

example 3

[0067]A process similar to Example 1 was repeated except that the core layer included about 81 wt % of crystalline 4032D, 15 wt % of amorphous PLA 4060D, and 4 wt % of ethylene-acrylate copolymer. The transverse orientation rate obtained was 9.0×.

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Abstract

A biaxially oriented laminate film including a first amorphous polylactic acid polymer heat sealable resin layer and a second core layer including a blend of crystalline polylactic acid polymer and 2-10 wt % of the core layer of an ethylene-acrylate copolymer. The laminate film, exhibiting the property to be transverse oriented in excess of 6 times its original width, typically 8 to 10 times its original width with excellent operability and relatively low haze, is disclosed. The laminate film may further have additional layers such as a third polylactic acid resin-containing layer disposed on the side of the core layer opposite the heat sealable layer, a metal layer, or combinations thereof.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. provisional application No. 60 / 996,923, filed on Dec. 11, 2007, the entire content of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]This invention relates to a multi-layer biaxially oriented polylactic acid (BOPLA) film with a novel formulation which exhibits significantly improved ability to stretch in the transverse direction in a biaxial orientation process.BACKGROUND OF THE INVENTION[0003]Biaxially oriented polypropylene (BOPP) films used for packaging, decorative, and label applications often perform multiple functions. For example, in laminations they can provide printability, transparent or matte appearance, and / or slip properties. They can further be used to provide a surface suitable for receiving organic or inorganic coatings for gas and moisture barrier properties. They can also be used to provide a heat sealable layer for bag forming and sealing, or a layer th...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B27/06B32B27/36B29C47/06B29C48/08B29C48/18
CPCB29C47/0021B32B2553/00B29C55/023B29C55/143B29C55/16B29K2023/08B29K2023/083B29K2033/08B29K2067/046B29K2105/0085B29K2995/006B29L2009/00B32B27/308B32B27/36B32B2250/24B32B2270/00B32B2307/702B32B2307/704B32B2307/7163B32B27/08B32B27/32B32B2255/10B32B2255/205B32B2307/412B32B2307/518B32B2451/00B29C47/06B29C48/08B29C48/18Y10T428/31786
Inventor LEE, MARK S.
Owner TORAY PLASTICS AMERICA
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